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Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

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At least 1,765 records · Page 98Linked to original sources

USGS1977

Fall migration of woodcock at Cape May, New Jersey

From 1968 to 1973, 2,337 American woodcock ( Philohela minor ) were banded during late fall on the Cape May Peninsula of southern New Jersey. Direct recovery rates averaged 3.6 percent for hatching-year birds and 1.7 percent for adults. Distribution of recoveries indicated that Cape May migrants wintered on the coastal plain of Virginia and North Carolina. Indirect recoveries showed that Peninsula woodcock originated from as far north as New England and eastern Canada. The percentage of woodcock seen which were caught by night-lighting averaged 2.5 times greater from a truck than on foot. Age-sex structure of ban dings was similar each year with the overall composition as follows: immaturemales, 57 percent; immature females, 28 percent; adult males, 10 percent; and adult females, 5 percent. Compared to the continental population, there was an unusually high proportion of immature woodcock at Cape May during late fall.

New Jersey↗

USGS2000

Puerto Rico: Marine sediments, terrestrial and seafloor imagery, and tectonic interpretations

Introduction: Puerto Rico is an island situated in the plate boundary zone between the Caribbean and the North American Plates. This is a geologically fascinating, tectonically active region, where the Caribbean Plate has over-ridden the North American Plate and is now sliding past it with strike-slip motion. The details of this tectonic interaction are poorly understood, largely because much of the region lies under water, making it difficult to study. The geologic setting of Puerto Rico has created or contributed to several pressing societal issues, related to human safety, environmental health, and economic development. Because the island lies on an active plate boundary, earthquakes are a constant threat and the densely populated coastal areas are vulnerable to tsunamis. Coastal erosion is a concern in many coastal areas, but is particularly serious to an island economy which relies heavily on a thriving tourist industry. In Puerto Rico, illegal mining of beach sands for use as aggregate has exacerbated coastal erosion and left coastal communities more exposed to the ravages of storms and tsunamis. The serious need for an affordable local source of aggregate to use in the growing construction industry on the island has created a strong interest in locating and evaluating offshore sand and gravel deposits. During the last 20 years the U.S. Geological Survey, often in cooperation with the Puerto Rico Department of Natural Resources and/or the University of Puerto Rico, has conducted a variety of projects to address the geologic aspects of these pressing societal issues. The papers and data presented here are the results of these projects. Some have been previously published elsewhere; others, such as the database of surficial sediments of the Puerto Rico insular shelf, interpretation of side-looking airborne radar imagery of the island, and the GIS data, are presented here for the first time. The purpose of this CD is to make the results of these diverse studies available in a readily accessible digital form, so that managers, planners, and other researchers can utilize the results.

Puerto Rico↗

USGS2014

Regional regression equations for the estimation of selected monthly low-flow duration and frequency statistics at ungaged sites on streams in New Jersey

Regional regression equations were developed for estimating monthly flow-duration and monthly low-flow frequency statistics for ungaged streams in Coastal Plain and non-coastal regions of New Jersey for baseline and current land- and water-use conditions. The equations were developed to estimate 87 different streamflow statistics, which include the monthly 99-, 90-, 85-, 75-, 50-, and 25-percentile flow-durations of the minimum 1-day daily flow; the August–September 99-, 90-, and 75-percentile minimum 1-day daily flow; and the monthly 7-day, 10-year (M7D10Y) low-flow frequency. These 87 streamflow statistics were computed for 41 continuous-record streamflow-gaging stations (streamgages) with 20 or more years of record and 167 low-flow partial-record stations in New Jersey with 10 or more streamflow measurements. The regression analyses used to develop equations to estimate selected streamflow statistics were performed by testing the relation between flow-duration statistics and low-flow frequency statistics for 32 basin characteristics (physical characteristics, land use, surficial geology, and climate) at the 41 streamgages and 167 low-flow partial-record stations. The regression analyses determined drainage area, soil permeability, average April precipitation, average June precipitation, and percent storage (water bodies and wetlands) were the significant explanatory variables for estimating the selected flow-duration and low-flow frequency statistics. Streamflow estimates were computed for two land- and water-use conditions in New Jersey—land- and water-use during the baseline period of record (defined as the years a streamgage had little to no change in development and water use) and current land- and water-use conditions (1989–2008)—for each selected station using data collected through water year 2008. The baseline period of record is representative of a period when the basin was unaffected by change in development. The current period is representative of the increased development of the last 20 years (1989–2008). The two different land- and water-use conditions were used as surrogates for development to determine whether there have been changes in low-flow statistics as a result of changes in development over time. The State was divided into two low-flow regression regions, the Coastal Plain and the non-coastal region, in order to improve the accuracy of the regression equations. The left-censored parametric survival regression method was used for the analyses to account for streamgages and partial-record stations that had zero flow values for some of the statistics. The average standard error of estimate for the 348 regression equations ranged from 16 to 340 percent. These regression equations and basin characteristics are presented in the U.S. Geological Survey (USGS) StreamStats Web-based geographic information system application. This tool allows users to click on an ungaged site on a stream in New Jersey and get the estimated flow-duration and low-flow frequency statistics. Additionally, the user can click on a streamgage or partial-record station and get the “at-site” streamflow statistics. The low-flow characteristics of a stream ultimately affect the use of the stream by humans. Specific information on the low-flow characteristics of streams is essential to water managers who deal with problems related to municipal and industrial water supply, fish and wildlife conservation, and dilution of wastewater.

New Jersey↗

USGS2001

Abstracts from "Coastal Marsh Dieback in the Northern Gulf of Mexico: Extent, Causes, Consequences, and Remedies

In the spring of 2000, scientists discovered a new and unprecedented loss of salt marsh vegetation in coastal Louisiana and other areas along the northern coast of the Gulf of Mexico. This dieback of salt marsh vegetation, sometimes called the brown marsh phenomenon', primarily involved the rapid browning and dieback of smooth cordgrass (Spanina alterniflora). Coastal Louisiana has already undergone huge, historical losses of coastal marsh due to both human-induced and natural factors, and the current overall rate of wetland loss (25-35 sq mi 65-91 SQ KM each year) stands to threaten Louisiana's coastal ecosystem, infrastructure, and economy. On January 11-12, 2001, individuals from Federal and State agencies, universities, and the private sector met at the conference 'Coastal Marsh Dieback in the Northern Gulf of Mexico: Extent, Causes, Consequences, and Remedies' to discuss and share information shout the marsh dieback. Presentations discussed trends in the progress of dieback during the summer of 2000 and in environmental conditions occurring at field study sites, possible causes including drought and Mississippi low flow' conditions, changes in soil conditions (salinity, the bioavailability of metals, pathogens, etc.), the potential for wetland loss that could occur if above and below normality occurs and is sustained over an extended period, advanced techniques for tracking the dieback via aerial photography and remote sensing, linkages of marsh hydrology to the dieback, and mechanisms of modeling dieback and recovery. In addition, presentations were made regarding development of a web site to facilitate information sharing and progress in preparation for requests for proposals based on an emergency appropriation by the U.S. Congress. All findings tended to support the idea that the dieback constituted a continuing environmental emergency and research and natural resource management efforts should be expended accordingly.

Information and Technology Report↗

USGS1996

Demography of Northern Spotted Owls in southwestern Oregon

Northern Spotted Owls ( Strix occidentalis caurina ) are associated with lower elevation, commercially valuable, late-successional coniferous forests in the Pacific Northwest. Meta-analyses of demographic parameters indicate that Northern Spotted Owl populations are declining throughout their range (Anderson and Burnham 1992, Burnham et al. this volume). Recent research has attempted to determine whether management activities have affected the viability of Spotted Owl populations, and results have led to development of conservation plans for the species (Dawson et al. 1987, Thomas et al. 1990, Murphy and Noon 1992, USDI 1992, Thomas et al. 1993b). In the Recovery Plan for the Northern Spotted Owl (USDI 1992b) threats to the species were identified as small population sizes, declining populations, limited amounts of habitat, continued loss and fragmentation of habitat, geographically isolated populations, and predation and competition from other avian species. Weather and fire are natural processes that also may affect reproductive success of Spotted Owls. Weather may be a factor in the high annual variability in fecundity of Spotted Owls, as has been suggested for other predatory bird species (Newton, 1979, 1986). However, these factors have not been addressed in previous studies of Spotted Owls. Our objectives were to estimate survival, fecundity, and annual rates of population change (l) for resident, territorial female Spotted Owls at two study areas in the coastal mountains of southwestern Oregon. We tested if the amount of rainfall was correlated with reproduction of Spotted Owls. While surveying for Spotted Owls, we documented the increased presence of Barred Owls ( Strix varia ), a potential competitor of Spotted Owls.

Oregon↗

USGS2013

The silent threat of low genetic diversity

Across the Caribbean, protected coastal waters have served as primary feeding and breeding grounds for the endangered Antillean manatee. Unfortunately, these same coastal waters are also a popular “habitat” for humans. In the past, the overlap between human and manatee habitat allowed for manatee hunting and threatened the survival of these gentle marine mammals. Today, however, threats are much more inadvertent and are often related to coastal development, degraded habitats and boat strikes. In the state of Florida, decades of research on the species’ biological needs have helped conservationists address threats to its survival. For example, low wake zones and boater education have protected manatees from boat strikes, and many of their critical winter refuges are now protected. The Florida population has grown steadily, thus increasing from approximately 1,200 in 1991 to more than 5,000 in 2010. It is conceivable that in Florida manatees may one day be reclassified as “threatened” rather than “endangered.” Yet, in other parts of the Caribbean, threats still loom. This includes small, isolated manatee populations found on islands that can be more susceptible to extinction and lack of genetic diversity. To ensure the species’ long-term viability, scientists have turned their sights to the overall population dynamics of manatees throughout the Caribbean. Molecular genetics has provided new insights into long-term threats the species faces. Fortunately, the emerging field of conservation genetics provides managers with tools and strategies for protecting the species’ long-term viability.

livebetter Magazine↗

USGS2021

Growth of greater white-fronted goose goslings relates to population dynamics at multiple scales

The abundance of greater white-fronted geese ( Anser albifrons frontalis ) on the Arctic Coastal Plain (ACP) of northern Alaska, USA, has more than tripled since the late 1990s; however, recent rate of annual population growth has declined as population size increased, which may indicate white-fronted geese on the ACP are approaching carrying capacity. We examined rates of gosling growth in greater white-fronted geese at 3 sites on the ACP during 2012–2014 to assist with predictions of future population trends and assess evidence for density-dependent constraints on recruitment. We marked goslings at hatch with individually coded webtags and conducted brood drives during early August to capture, measure, and weigh goslings. Annual estimates of gosling mass at 32 days old (range = 1,190–1,685) indicate that goslings had obtained >60% of asymptotic size. This rate of growth corresponds with that of other goose species and populations with access to high-quality forage and no limitations on forage availability, and is consistent with the overall increase in abundance of white-fronted geese at the ACP scale. Contrary to most previous investigations, age-adjusted mass of goslings did not decline with hatch date. Goslings grew faster in coastal areas than at inland freshwater sites. Taken together, these findings suggest forage was not limiting gosling growth rates in either ecosystem, but forage was of greater quality in coastal areas where goose foraging habitat is expanding because of permafrost subsidence. Spatial patterns of gosling growth corresponded with local-scale patterns of population density and population change; the areas with greatest rates of gosling growth were those with the greatest population density and rates of population increase. We found little evidence to suggest forage during brood rearing was limiting population increase of white-fronted geese on the ACP. Factors responsible for the apparent slowing of ACP-wide population growth are likely those that occur in stages of the annual cycle outside of the breeding grounds.

Alaska↗

USGS2024

The projected exposure and response of a natural barrier island system to climate-driven coastal hazards

Accelerating sea level rise (SLR) and changing storm patterns will increasingly expose barrier islands to coastal hazards, including flooding, erosion, and rising groundwater tables. We assess the exposure of Cape Lookout National Seashore, a barrier island system in North Carolina (USA), to projected SLR and storm hazards over the twenty-first century. We estimate that with 0.5 m of SLR, 47% of current subaerial barrier island area would be flooded daily, and the 1-year return period storm would flood 74%. For 20-year return period storms, over 85% is projected to be flooded for any SLR. The modelled groundwater table is already shallow (< 2 m deep), and while projected to shoal to the land surface with SLR, marine flooding is projected to overtake areas with emergent groundwater. Projected shoreline retreat reaches an average of 178 m with 1 m of SLR and no interventions, which is over 60% of the current island width at narrower locations. Compounding these hazards is subsidence, with one-third of the study area currently lowering at > 2 mm/yr. Our results demonstrate the difficulty of managing natural barrier systems such as those managed by federal park systems tasked with maintaining natural ecosystems and protecting cultural resources.

North Carolina↗

USGS2022

Habitat connectivity and host relatedness influence virus spread across an urbanising landscape in a fragmentation-sensitive carnivore

Spatially heterogeneous landscape factors such as urbanisation can have substantial effects on the severity and spread of wildlife diseases. However, research linking patterns of pathogen transmission to landscape features remains rare. Using a combination of phylogeographic and machine learning approaches, we tested the influence of landscape and host factors on feline immunodeficiency virus (FIV Lru ) genetic variation and spread among bobcats ( Lynx rufus ) sampled from coastal southern California. We found evidence for increased rates of FIV Lru lineage spread through areas of higher vegetation density. Furthermore, single-nucleotide polymorphism (SNP) variation among FIV Lru sequences was associated with host genetic distances and geographic location, with FIV Lru genetic discontinuities precisely correlating with known urban barriers to host dispersal. An effect of forest land cover on FIV Lru SNP variation was likely attributable to host population structure and differences in forest land cover between different populations. Taken together, these results suggest that the spread of FIV Lru is constrained by large-scale urban barriers to host movement. Although urbanisation at fine spatial scales did not appear to directly influence virus transmission or spread, we found evidence that viruses transmit and spread more quickly through areas containing higher proportions of natural habitat. These multiple lines of evidence demonstrate how urbanisation can change patterns of contact-dependent pathogen transmission and provide insights into how continued urban development may influence the incidence and management of wildlife disease.

California↗

USGS2018

Measuring and evaluating ecological flows from streams to regions: Steps towards national coverage

Living aquatic communities are largely determined and maintained by the volume and quality of flowing waters, both within lotic systems and in receiving waters of coastal systems. However, flow is one of the most frequently and extensively altered features of rivers and streams; alteration effects are likely to be exacerbated by climate change. Lotic systems vary and different fish species need different environmental conditions, and distinct problems are evident at various spatial scales. New synoptic flow and biological information now make it possible to evaluate the effects of altered flows throughout the Great Lakes Region at scales from the stream reach to the Region. We used estimates of river and streamflow and observed fish abundances to develop tools that specify the response of fish to alterations in those flows. We fit the logistic model to a cumulative fish abundance curve as a function of yield providing an empirical means to develop models of the response of cumulative fish abundance to flows. Response zones of yield for each species in each system type (based on size and thermal class) illustrate how criteria may be developed that can be used in decision‐making for management of flows. In our example application, we evaluate both the general response of brook trout ( Salvelinus fontinalis ) abundances (and fish diversity) to changes in flows and assess the sensitivity of each stream fish community to flow alteration. Mapping stream sensitivity to flow alteration throughout the US Great Lakes Region with a multiscale spatial framework showed how regional variability in sensitivity for any fish species or assemblage may be evaluated and provides managers with information to help determine where the best opportunities for protection or restoration of streamflows and associated communities exist. These results provide valuable tools and critical information to managers responsible for balancing water uses and maintaining high quality lotic ecosystems. These methods may be applied to any geographic region and can be extended nationally or globally, where flow, temperature, fish and landscape data are available.

Illinois, Indiana, Michigan, Minnesota, New York, ↗

USGS2017

A three-dimensional mapping of the ocean based on environmental data

The existence, sources, distribution, circulation, and physicochemical nature of macroscale oceanic water bodies have long been a focus of oceanographic inquiry. Building on that work, this paper describes an objectively derived and globally comprehensive set of 37 distinct volumetric region units, called ecological marine units (EMUs). They are constructed on a regularly spaced ocean point-mesh grid, from sea surface to seafloor, and attributed with data from the 2013 World Ocean Atlas version 2. The point attribute data are the means of the decadal averages from a 57-year climatology of six physical and chemical environment parameters (temperature, salinity, dissolved oxygen, nitrate, phosphate, and silicate). The database includes over 52 million points that depict the global ocean in x, y, and z dimensions. The point data were statistically clustered to define the 37 EMUs, which represent physically and chemically distinct water volumes based on spatial variation in the six marine environmental characteristics used. The aspatial clustering to produce the 37 EMUs did not include point location or depth as a determinant, yet strong geographic and vertical separation was observed. Twenty-two of the 37 EMUs are globally or regionally extensive, and account for 99% of the ocean volume, while the remaining 15 are smaller and shallower, and occur around coastal features. We assessed the vertical distribution of EMUs in the water column and placed them into classical depth zones representing epipelagic (0 m to 200 m), mesopelagic (200 m to 1,000 m), bathypelagic (1,000 m to 4,000 m) and abyssopelagic (>4,000 m) layers. The mapping and characterization of the EMUs represent a new spatial framework for organizing and understanding the physical, chemical, and ultimately biological properties and processes of oceanic water bodies. The EMUs are an initial objective partitioning of the ocean using long-term historical average data, and could be extended in the future by adding new classification variables and by introducing functionality to develop time-specific EMU distribution maps. The EMUs are an open-access resource, and as both a standardized geographic framework and a baseline physicochemical characterization of the oceanic environment, they are intended to be useful for disturbance assessments, ecosystem accounting exercises, conservation priority setting, and marine protected area network design, along with other research and management applications.

Oceanography↗

USGS2015

Sensitivity of tsunami evacuation modeling to direction and land cover assumptions

Although anisotropic least-cost-distance (LCD) modeling is becoming a common tool for estimating pedestrian-evacuation travel times out of tsunami hazard zones, there has been insufficient attention paid to understanding model sensitivity behind the estimates. To support tsunami risk-reduction planning, we explore two aspects of LCD modeling as it applies to pedestrian evacuations and use the coastal community of Seward, Alaska, as our case study. First, we explore the sensitivity of modeling to the direction of movement by comparing standard safety-to-hazard evacuation times to hazard-to-safety evacuation times for a sample of 3985 points in Seward's tsunami-hazard zone. Safety-to-hazard evacuation times slightly overestimated hazard-to-safety evacuation times but the strong relationship to the hazard-to-safety evacuation times, slightly conservative bias, and shorter processing times of the safety-to-hazard approach make it the preferred approach. Second, we explore how variations in land cover speed conservation values (SCVs) influence model performance using a Monte Carlo approach with one thousand sets of land cover SCVs. The LCD model was relatively robust to changes in land cover SCVs with the magnitude of local model sensitivity greatest in areas with higher evacuation times or with wetland or shore land cover types, where model results may slightly underestimate travel times. This study demonstrates that emergency managers should be concerned not only with populations in locations with evacuation times greater than wave arrival times, but also with populations with evacuation times lower than but close to expected wave arrival times, particularly if they are required to cross wetlands or beaches.

Applied Geography↗

USGS2020

Spatially referenced models of streamflow and nitrogen, phosphorus, and suspended-sediment loads in streams of the northeastern United States

SPAtially Referenced Regression On Watershed attributes (SPARROW) models were developed to quantify and improve the understanding of the sources, fate, and transport of nitrogen, phosphorus, and suspended sediment in the northeastern United States. Excessive nutrients and suspended sediment from upland watersheds and tributary streams have contributed to ecological and economic degradation of northeastern surface waters. Recent efforts to reduce the flux of nutrients and suspended sediment in northeastern streams and to downstream estuaries have met with mixed results, and expected ecological improvements have been observed in some areas but not in others. Effective watershed management and restoration to improve surface-water quality are complicated by the multitude of nutrient sources in the Northeast and the multitude of natural and human landscape processes affecting the delivery of nutrients and suspended sediment from upland areas to and within surface waters. Individual models were constructed representing streamflow and the loads of total nitrogen, total phosphorus, and suspended sediment from watersheds draining to the Atlantic Ocean from southern Virginia through Maine. Northeastern streams contribute 303,000 metric tons (t) of nitrogen, 25,300 t of phosphorus, and 14,700,000 t of suspended sediment, annually (on average), to waters along the Atlantic Coast of North America. Although atmospheric deposition and natural mineral erosion contribute to nitrogen and phosphorus loads, respectively, in northeastern streams, most of the contributions are attributable to urban or agricultural sources. Within the Northeast, average yields of nutrients are therefore generally greater from densely populated or intensively cultivated areas of the mid-Atlantic region, the Hudson, Mohawk, and Connecticut River valleys, and the coastal areas of southern New England than in predominantly forested areas such as northern New England. Average upland sediment yields are similarly greater from agricultural areas than from urban or forested areas and are therefore generally greatest in areas yielding the greatest nutrients. Landscape conditions that are significant to nitrogen delivery from uplands to streams likely reflect the importance of groundwater transport in carbonate settings and of denitrification for removing nitrogen from uplands. Nitrogen losses to streams in agricultural areas are apparently mitigated by the use of cover crops but are exacerbated by the use of conservation tillage or no-till practices. The transport of phosphorus and suspended sediment from uplands to streams is greater in areas of more erodible soils but mitigated in agricultural areas with greater use of conservation tillage or no-till practices. Loads of nutrients and suspended sediment are significantly reduced within the stream network in impounded reaches, and nitrogen load is also significantly reduced in small flowing reaches.

Scientific Investigations Report↗

USGS2016

Potential effects of alterations to the hydrologic system on the distribution of salinity in the Biscayne aquifer in Broward County, Florida

To address concerns about the effects of water-resource management practices and rising sea level on saltwater intrusion, the U.S. Geological Survey in cooperation with the Broward County Environmental Planning and Community Resilience Division, initiated a study to examine causes of saltwater intrusion and predict the effects of future alterations to the hydrologic system on salinity distribution in eastern Broward County, Florida. A three-dimensional, variable-density solute-transport model was calibrated to conditions from 1970 to 2012, the period for which data are most complete and reliable, and was used to simulate historical conditions from 1950 to 2012. These types of models are typically difficult to calibrate by matching to observed groundwater salinities because of spatial variability in aquifer properties that are unknown, and natural and anthropogenic processes that are complex and unknown; therefore, the primary goal was to reproduce major trends and locally generalized distributions of salinity in the Biscayne aquifer. The methods used in this study are relatively new, and results will provide transferable techniques for protecting groundwater resources and maximizing groundwater availability in coastal areas. The model was used to (1) evaluate the sensitivity of the salinity distribution in groundwater to sea-level rise and groundwater pumping, and (2) simulate the potential effects of increases in pumping, variable rates of sea-level rise, movement of a salinity control structure, and use of drainage recharge wells on the future distribution of salinity in the aquifer. Results from the simulation of historical conditions indicate that the model generally represents the observed greater westward extent of elevated salinity in the central part of the intruded area relative to the northern and southernmost parts of the intruded area. Results of sensitivity testing indicate that the extent of elevated salinity is most sensitive to pumping in areas where the source of saltwater is largely offshore, from the Atlantic Ocean, and is most sensitive to sea-level rise in areas where the source of salinity is downward leakage of brackish water from canals. Simulations of future scenarios indicate that increases in pumping near the existing interface may cause the interface to advance and decreases in pumping may cause it to retreat. Climatic effects, such as periods of prolonged drought or high precipitation, may augment or counteract long-term effects of changes in pumping on aquifer salinity at well fields. With increasing rates of sea-level rise, the freshwater-saltwater interface advances progressively inland, and flow-averaged salinities at well fields near the existing interface increase commensurately. Hypothetical southeastward (downstream) re-positioning of the existing G–54 salinity-control structure may prevent the interface from moving northwestward along and near the North New River canal, but beneficial effects are localized. Implementation of freshwater recharge wells in the city of Hallandale Beach may also have only a localized freshening effect in the aquifer and little appreciable effect on the freshwater-saltwater interface or on concentrations of salinity at well fields. Model accuracy and use are limited by uncertainty in the physical properties and boundary conditions of the system, uncertainty in historical and future conditions, and generalizations made in the mathematical relationships used to describe the physical processes of groundwater flow and transport. Because of these limitations, model results should be considered in relative rather than absolute terms. Nonetheless, model results do provide useful information on the relative scale of response of the system to changes in pumping distribution, sea-level rise, and mitigation activities.

Florida↗

USGS2014

Reduced disease in black abalone following mass mortality: Phage therapy and natural selection

Black abalone, Haliotis cracherodii , populations along the NE Pacific ocean have declined due to the rickettsial disease withering syndrome (WS). Natural recovery on San Nicolas Island (SNI) of Southern California suggested the development of resistance in island populations. Experimental challenges in one treatment demonstrated that progeny of disease-selected black abalone from SNI survived better than did those from naïve black abalone from Carmel Point in mainland coastal central California. Unexpectedly, the presence of a newly observed bacteriophage infecting the WS rickettsia (WS-RLO) had strong effects on the survival of infected abalone. Specifically, presence of phage-infected RLO (RLOv) reduced the host response to infection, RLO infection loads, and associated mortality. These data suggest that the black abalone: WS-RLO relationship is evolving through dual host mechanisms of resistance to RLO infection in the digestive gland via tolerance to infection in the primary target tissue (the post-esophagus) coupled with reduced pathogenicity of the WS-RLO by phage infection, which effectively reduces the infection load in the primary target tissue by half. Sea surface temperature patterns off southern California, associated with a recent hiatus in global-scale ocean warming, do not appear to be a sufficient explanation for survival patterns in SNI black abalone. These data highlight the potential for natural recovery of abalone populations over time and that further understanding of mechanisms governing host–parasite relationships will better enable us to manage declining populations.

California↗

USGS2024

Improving how science informs policy within the Ecosystem Approach

Science is fundamental to sound policies, particularly when it comes to implementing an Ecosystem Approach. Science can and should inform nearly all facets of an Ecosystem Approach, yet challenges remain to realizing this goal. To help identify and better understand these challenges we used a qualitative comparative case study approach to identify and characterize the challenges and successes of implementing a science-driven Ecosystem Approach in the Laurentian Great Lakes. These case studies include delisting of Areas of Concern, improving coastal resilience, and addressing declining offshore lake productivity. These case studies were selected because they provide a set of very different, yet complementary, cases for assessing implementation, as well as the factors influencing the science-policy exchange. Through this comparative study, we identified a diverse set of challenges and successes, that were both systemic and case specific. Emerging from this comparative assessment were principles and enabling conditions (e.g. scale, governance, shared goals) we believe are critical to consider when establishing or improving a science-driven Ecosystem Approach.

Aquatic Ecosystem Health & Management↗

USGS2020

Improved fish counting method accurately quantifies high‐density fish movement in dual‐frequency identification sonar data files from a coastal wetland environment

There are many ways to quantify fish movement through shallow‐water habitats, but most noninvasive methods (e.g., visual counts) are not effective in turbid coastal wetland waters of the Great Lakes. Dual‐frequency identification sonar (DIDSON) technology (Sound Metrics) offers a noninvasive, hydroacoustic‐based approach to characterize fish movement in wetlands and other habitats by collecting highly detailed fish movement data regardless of light and water quality conditions. High‐resolution data can be analyzed to estimate fish movement in areas where visual observations are difficult. However, enumerating a complex mix of fish sizes by manually counting fish visible in echogram files requires training and is very time consuming. Therefore, four counting techniques were tested to estimate fish abundance from DIDSON echograms that were collected at a hydrologically reconnected coastal wetland in the Great Lakes. Briefly, the four counting methods were (1) manually viewing the entire length of the echogram (full‐hour manual count), (2) manually viewing subsections of the echogram before generating fish estimates by per‐minute average (subsample manual count), (3) using Echoview automated software to generate automated estimates, and (4) using DIDSON viewer software to generate automated estimates. Over 800 echogram‐hours were recorded over a 9‐month period at an open‐flow water control structure connecting a coastal wetland to a tributary to Lake Erie. Commercial fish tracking software (Echoview) and custom software scripts from Milne Technologies were used to semi‐automate fish count estimates for a small subset of data. Semi‐automated software counts were compared to manual counts of identical data files to assess differences in accuracy, cost, processing time, and counter effort. Semi‐automated fish count estimates using Echoview and custom pre‐ and postprocessing software scripts did not differ from baseline manual counts, suggesting that the semi‐automated count process could be a reliable tool to increase efficiency when processing large DIDSON data sets.

Great Lakes↗

USGS2026

Spatially referenced watershed models for the binational Red–Assiniboine River Basin: Bayesian vs frequentist comparison

Excess nutrient loading remains a leading cause of declining water quality in lakes, estuaries, and coastal waters worldwide, with global economic costs of US$200 billion – US$2 trillion annually from impacts on fisheries, tourism, freshwater resources, and water treatment. Our study focuses on total phosphorus (TP) in Lake Winnipeg and its binational Red-Assiniboine River Basin, where nutrient inputs have degraded water quality and increased cyanobacterial blooms. These changes pose ecological, public health, and economic risks. We applied a spatially referenced watershed model with a hybrid statistical-mechanistic structure partitioning annual nutrient loads into land-use export, land-to-water delivery, and in-reservoir decay. Bayesian and traditional frequentist model calibrations were compared. In the frequentist model, coefficients for agricultural inputs, forests /wetlands, stream channels, precipitation, and reservoir losses were statistically significant, whereas coefficient for wastewater was not. In contrast, all variables were successfully calibrated using the Bayesian approach. Model results delineate TP-export hotspots across the basin, showing that 54–62% of TP originates from the U.S., with agricultural sources ranging 62–72%—highlighting the importance of agriculture-focused Best Management Practices. Given the global relevance of nutrient-driven water-quality challenges, our results highlight Bayesian calibration for robust risk assessment and adaptive nutrient management.

Red–Assiniboine River Basin↗